import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: GaoBo
 * Date: 2021-06-06
 * Time: 8:25
 */


/*
class Solution {
    public boolean isValid(String s) {
        if(s == null || s.length() == 0) {
            return true;
        }

        //1、定义一个栈，来存放左括号
        Stack<Character> stack = new Stack<>();

        //2、开始遍历当前的字符串s
        for(int i = 0;i < s.length();i++) {
            //获取当前i小标是一个啥字符
            char ch = s.charAt(i);
            //判断当前的字符是哪个左括号，因为题上说 只有3种左括号。
            if(ch == '(' || ch == '[' || ch == '{') {
                stack.push(ch);
            }else{
                //进入else 说明当前i下标是一个右括号
                //但是 判断栈空不空
                if(stack.empty()) {
                   System.out.println("右括号多！");
                   return false;
                }

                //获取栈顶元素的括号，但是先别出栈
                char tmp = stack.peek();
                if(tmp == '{' && ch == '}' || tmp == '[' && ch == ']' || tmp == '(' && ch == ')' ){
                    //出栈当前的左括号，说明匹配成功
                    stack.pop();
                }else{
                   System.out.println("左右括号不匹配！");
                   return false;
                }
            }
        }
        //把字符串遍历完了，但是栈还不是空的
        if(!stack.empty()) {
            System.out.println("左括号多！");
            return false;
        }
       System.out.println("左右括号匹配！");
        return true;
    }
}


==============================


 */

class MyStack {

    private Queue<Integer> qu1;
    private Queue<Integer> qu2;
    /** Initialize your data structure here. */
    public MyStack() {
        qu1 = new LinkedList<>();
        qu2 = new LinkedList<>();
    }

    /** Push element x onto stack. */
    public void push(int x) {
        if(!qu1.isEmpty()) {
            qu1.offer(x);
        }else if(!qu2.isEmpty()) {
            qu2.offer(x);
        }else{
            //两个队列都为空  目前指定放到第一个队列当中
            qu1.offer(x);
        }
    }

    /** Removes the element on top of the stack and returns that element. */
    public int pop() {
        if(empty()) return -1;
        if(!qu1.isEmpty()) {
            int size =qu1.size();
            for(int i = 0;i < size-1;i++) {
                int x = qu1.poll();
                qu2.offer(x);
            }
            return qu1.poll();
        }else {
            int size =qu2.size();
            for(int i = 0;i < size-1;i++) {
                int x = qu2.poll();
                qu1.offer(x);
            }
            return qu2.poll();
        }
    }

    /** Get the top element. */
    public int top() {
        if(empty()) return -1;
        if(!qu1.isEmpty()) {
            int size = qu1.size();
            int x = -1;
            for(int i = 0;i < size;i++) {
                x = qu1.poll();
                qu2.offer(x);
            }
            return x;
        }else{
            int size = qu2.size();
            int x  = -1;
            for(int i = 0;i < size;i++) {
                x = qu2.poll();
                qu1.offer(x);
            }
            return x;
        }
    }

    /** Returns whether the stack is empty. */
    public boolean empty() {
        return qu1.isEmpty() && qu2.isEmpty();
    }
}

class A {

}
class B extends A {

}
class C extends B{

}



public class TesteDemo {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.next();
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);//每拿到一个字符就判断
            if(!sb.toString().contains(ch+"")) {
                sb.append(ch);
            }
        }
        System.out.println(sb);
    }

    public static void main2(String[] args) {
        LinkedList<Integer> linkedList = new LinkedList<>();
        linkedList.isEmpty();


       Object o  = new Object(){
            @Override
            public boolean equals(Object obj) {
                return true;
            }
        };
        System.out.println(o.equals("gaobo"));
    }
    public static void main1(String[] args) {
        A a = new B();
        A a1 = new C();
        B b = new C();
    }
}
